diff options
Diffstat (limited to 'en_US.ISO8859-1/articles/ipsec-must/article.sgml')
| -rw-r--r-- | en_US.ISO8859-1/articles/ipsec-must/article.sgml | 297 |
1 files changed, 0 insertions, 297 deletions
diff --git a/en_US.ISO8859-1/articles/ipsec-must/article.sgml b/en_US.ISO8859-1/articles/ipsec-must/article.sgml deleted file mode 100644 index 716ce5df5b..0000000000 --- a/en_US.ISO8859-1/articles/ipsec-must/article.sgml +++ /dev/null @@ -1,297 +0,0 @@ -<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> - -<html> - <head> - <title>Independent Verification of IPSec Functionality in FreeBSD</title> - </head> - - <body text="#000000" bgcolor="#FFFFFF"> - - <h1>Independent Verification of IPsec Functionality Under FreeBSD 3.0</h1> - - <p align="center"><i>You installed IPsec and it seems to be working. - How do you know? I describe a method for experimentally verifying - that IPsec is working</i></p> - - <h2>The Problem</h2> - - <p>First, let's assume you have <a href="#Installing IPsec">installed - <i>IPsec</i></a>. How do you know its <a href="#Caveat">working</a>? - Sure, your connection won't work if its misconfigured, and it will work - when you finally get it right. <i>Netstat</i> will list it. But can you - independently confirm it?</p> - - <h2>The Solution</h2> - - <p>First, some crypto-relevent info theory:</p> - - <ol> - <li> - <p>Encrypted data is uniformly distributed, ie, has maximal entropy - per symbol.</p> - </li> - - <li> - <p>Raw, uncompressed data is typically redundant, i.e., has - sub-maximal entropy.</p> - </li> - </ol> - - <p>Suppose you could measure the entropy of the data to- and from- your - network interface. Then you could see the difference between unencrypted - data and encrypted data. This would be true even if some of the data - in "encrypted mode" was not encrypted ---as the outermost IP header must - be, if the packet is to be routable.</p> - - <h4><a name="MUST"></a>MUST</h4> - - <p>Ueli Maurer's "Universal Statistical Test for Random Bit Generators" - ("MUST") quickly measures the entropy of a sample. It uses a - compression-like algorithm. <a href="#Maurer's Universal Statistical - Test">The code is given below for a variant which measures successive - (~quarter megabyte) chunks of a file</a>.</p> - - <h4><a NAME="Tcpdump"></a>Tcpdump</h4> - - <p>We also need a way to capture the raw network data. A program called - "<i>tcpdump</i>" lets you do this, if you have enabled the <i>Berkeley - Packet Filter</i> interface in your <a - href="#usr/src/sys/i386/conf/KERNELNAME">kernel's config file</a>.</p> - - <p>The command</p> - - <blockquote><b>tcpdump</b> <b>-c</b> 4000 <b>-s</b> 10000 <b>-w</b> - <i>dumpfile.bin</i></blockquote> - - <p>will capture 4000 raw packets to <i>dumpfile.bin</i>. Up to 10,000 - bytes per packet will be captured in this example.</p> - - <h2>The Experiment</h2> - - <p>Here's the experiment. Open a window to an IPsec host and another - window to an insecure host.</p> - - <p>Now start <a href="#Tcpdump">capturing packets</a>.</p> - - <p>In the "secure" window, run the unix command "yes", which will stream - the "y" character. After a while, stop this. Switch to the insecure - window, and repeat. After a while, stop.</p> - - <p>Now run <a href="#Maurer's Universal Statistical Test">MUST</a> on the - captured packets. You should see something like the the following. - The important thing to note is that the secure connection has 93% (6.7) - of the expected value (7.18), and the "normal" connection has 29% (2.1) - of the expected value.</p> - - - <pre>% tcpdump -c 4000 -s 10000 -w ipsecdemo.bin -% uliscan ipsecdemo.bin - -Uliscan 21 Dec 98 -L=8 256 258560 -Measuring file ipsecdemo.bin -Init done -Expected value for L=8 is 7.1836656 -6.9396 -------------------------------------------------------- -6.6177 ----------------------------------------------------- -6.4100 --------------------------------------------------- -2.1101 ----------------- -2.0838 ----------------- -2.0983 -----------------</pre> - - <h2><a NAME="Caveat"></a>Caveat</h2> - - <p>This experiment shows that IPsec <i>does</i> seem to be distributing the - payload data <i>uniformly</i>, as encryption should. However, the - experiment described here <i>can not </i>detect many possible flaws in a - system (none of which do I have any evidence for). These include poor - key generation or exchange, data or keys being visible to others, use of - weak algorithms, kernel subversion, etc. Study the source; know the - code.</p> - - <h2><a NAME="IPsec"></a>IPsec -Definition</h2> - - <p>Internet Protocol security extensions to IP v 4; required for IP v6. A - protocol for negotiating encryption and authentication at the IP - (host-to-host) level. SSL secures only one application socket; SSH - secures only a login; PGP secures only a specified file or - message. IPsec encrypts everything between two hosts.</p> - - <h2><a NAME="Installing IPsec"></a>Installing IPsec</h2> - - <p>Starting from the BSD 3.0 stable release,</p> - - <ol> - <li> - <p>install IPsec v0.04, rebuild, reinstall</p> - </li> - - <li> - <p>run the administration tools (e.g, <i>ipsecadm</i>) and distribute - keys (or use <i>Photuris</i> for key exchange)</p> - </li> - - <li> - <p>set the routes (<i>rt</i>) up appropriately</p> - </li> - </ol> - - <p>You may want to make an "ipsec_setup" script containing the - <i>ipsecadm</i> and <i>rt</i> commands which establish your IPsec - tunnel. You can run this script automatically at boottime from your - <i>/etc/rc.local</i> The ipsec_setup script will have to contain at - least two <i>ipsecadm</i> commands and one <i>rt</i> command to be - useful.</p> - - <h2><a NAME="KERNELNAME"></a>usr/src/sys/i386/conf/KERNELNAME</h2> - - <p>This needs to be present in the kernel config file in order to run - IPsec. After adding it, run <i>config</i>, etc. and rebuild and - reinstall.</p> - - <pre># The `bpfilter' pseudo-device enables the Berkeley Packet Filter. Be -# aware of the legal and administrative consequences of enabling this -# option. Heh heh. The number of devices determines the maximum number of -# simultaneous BPF clients programs runnable. -pseudo-device bpfilter 2 #Berkeley packet filter - -# IPSEC -options IPSEC -options "MD5" -pseudo-device enc 1</pre> - - <h2><a name="must"></a>Maurer's Universal Statistical Test (for block - size=8 bits)</h2> - - <pre><![ CDATA [/* - ULISCAN.c ---blocksize of 8 - - 1 Oct 98 - 1 Dec 98 - 21 Dec 98 uliscan.c derived from ueli8.c - - This version has // comments removed for Sun cc - - This implements Ueli M Maurer's "Universal Statistical Test for Random - Bit Generators" using L=8 - - Accepts a filename on the command line; writes its results, with other - info, to stdout. - - Handles input file exhaustion gracefully. - - Ref: J. Cryptology v 5 no 2, 1992 pp 89-105 - also on the web somewhere, which is where I found it. - - -David Honig - honig@sprynet.com - - Usage: - ULISCAN filename - outputs to stdout -*/ - -#define L 8 -#define V (1<<L) -#define Q (10*V) -#define K (100 *Q) -#define MAXSAMP (Q + K) - -#include <stdio.h> -#include <math.h> - -int main(argc, argv) -int argc; -char **argv; -{ - FILE *fptr; - int i,j; - int b, c; - int table[V]; - double sum = 0.0; - int iproduct = 1; - int run; - - extern double log(/* double x */); - - printf("Uliscan 21 Dec 98 \nL=%d %d %d \n", L, V, MAXSAMP); - - if (argc < 2) { - printf("Usage: Uliscan filename\n"); - exit(-1); - } else { - printf("Measuring file %s\n", argv[1]); - } - - fptr = fopen(argv[1],"rb"); - - if (fptr == NULL) { - printf("Can't find %s\n", argv[1]); - exit(-1); - } - - for (i = 0; i < V; i++) { - table[i] = 0; - } - - for (i = 0; i < Q; i++) { - b = fgetc(fptr); - table[b] = i; - } - - printf("Init done\n"); - - printf("Expected value for L=8 is 7.1836656\n"); - - run = 1; - - while (run) { - sum = 0.0; - iproduct = 1; - - if (run) - for (i = Q; run && i < Q + K; i++) { - j = i; - b = fgetc(fptr); - - if (b < 0) - run = 0; - - if (run) { - if (table[b] > j) - j += K; - - sum += log((double)(j-table[b])); - - table[b] = i; - } - } - - if (!run) - printf("Premature end of file; read %d blocks.\n", i - Q); - - sum = (sum/((double)(i - Q))) / log(2.0); - printf("%4.4f ", sum); - - for (i = 0; i < (int)(sum*8.0 + 0.50); i++) - printf("-"); - - printf("\n"); - - /* refill initial table */ - if (0) { - for (i = 0; i < Q; i++) { - b = fgetc(fptr); - if (b < 0) { - run = 0; - } else { - table[b] = i; - } - } - } - } -}]]></pre> - </body> -</html> - - |